Many actuator position control applications require not only moving the actuator to a desired position, but also sustaining the actuator in the desired position for a period of time. Examples of such applications include, but are not limited to, exhaust gas recirculation (hereinafter sometimes EGR) valve control applications, variable geometry turbocharger (hereinafter sometimes VGT) mechanism control applications, exhaust gas wastegate valve control applications, exhaust gas throttle control applications, and the like. In such systems, a control system is typically implemented to control the position of the actuator.
In controlling an actuator to sustain a desired actuator position, the actuator current required to sustain the desired actuator position is generally understood to be proportional to the force applied to the actuator plus or minus the friction of the actuator positioning system. It is desirable under such conditions to control the actuator current to a value at or near the minimum current required to sustain the actuator in the desired position in order to maintain the actuator operating temperature below a specified maximum operating temperature.